The purpose of the Clinical Research Center for the Study of Senile Dementia (CRCSD) is to develop innovative studies of patients with Primary Degenerative Dementia (PDD), integrating five different specialty areas. A major theme of the CRCSD will be to identify areas of "excess disability" in PDD patients which may be alleviated to improve functional status. The projects are: Biochemical Component: This component will attempt to identify cerebrospinal fluid (CSF) biochemical markers for senile dementia which may be useful in the differential diagnosis of early forms of the disease from benign senescent forgetfulness and depression (pseudodementia). Particular attention will be directed towards newer peptide markers such as myelin basic protein, glial fibrillary acidic protein and amyloidogenic proteins. Electrophysiologic Component: This component will use electrophysiologic measures to follow the natural course of the disease with the intention of developing better methods of establishing diagnosis and prognosis. Sleep Component: This component will study the relation of disturbed sleep, alterd sleep-wake cycles, apneic episodes, daytime sleepiness, and "Sundowning," or nighttime confusion, to excess disability in PDD patients. For the first time a careful assessment of the clinical efficacy of several commonly used medications for "Sundowners" will be undertaken. Medical Component: This component will study the relation of medical illnesses which develop as PDD progresses to excess disability in elderly demented patients. Psychosocial Component: This component will study the course of psychosocial needs of caregivers of PDD patients and will attempt to develop model programs for treating depression in this group. One hundred patients with PDD will be followed for at least two years and evaluated on core congitive/behavioral measures using specialized testing from each Project. Each project will test important hypotheses within its specialty, however, hypotheses bridging specialized areas will also be tested, e.g., whether spinal fluid markers related to sleep disorders.